In the experimental study of nuclear physics, an invaluable tool includes the use of a particle accelerator and target. An accelerator having a storage ring configuration can generally keep the particle beam intact for sustained periods. A preferred form of target is of the internal type located in the ring, rather than an external type located on a dead end tangential offshoot from the ring. Often, an accelerator with an internal target is identified with respect to its internal target as a polarized internal target apparatus. In the internal target geometry, the beam can be recycled through the target. In use, the beam directed through the target would strike the target particles and scatter them, and this scatter would then be detected by sensor means located around the periphery of the target. Factors such as target density, beam density, etc., influence the scattering activity.
One important consideration in the selection of an internal target is the effect that multiple scattering will have on the electron beam. Based on this, the target thickness generally is limited. Also, polarization losses from ionization is an important factor in limiting the target thickness and in limiting the beam current.
Frequently, for polarized internal target apparatus, the target is hydrogen or heavy hydrogen (deuterium) gas. The atomic level of a hydrogen target gas will have a proton and an electron each having spins (S.sub.p, S.sub.e) according to any of the following four vector combinations: (1) plus plus; (2) plus minus; (3) minus minus: and (4) minus plus. These vector states are generally represented in approximately equal numbers in the natural state. The vector characterization of the spin protons S.sub.p and the spin electrons S.sub.e can be changed to make the target more sensitive to beam scattering. Under conventional theories, the more intensely polarized the target, the greater the sensitivity.
Accordingly, one object of the invention is an accelerator and particularly a polarized internal target apparatus having a target gas at a higher density and degree of polarization. A second object of the invention is an apparatus in which the degree of polarization of the target gas is achieved indirectly. Other objects will become apparent from the detailed description of the invention.